Organic-inorganic perovskites are attractive materials to be used as light harvesters in solar cells. A promising organic-inorganic perovskites to be used in solar cell is the organo-lead halide perovskites. They have direct band gap, large absorption coefficients [1,2] and high carrier mobility [3]. Their electronic properties can be tailored, allowing for the formation of layered materials, to control the distance and the electronic coupling between the inorganic sheets according to the structure of the organic component employed. The layered perovskites have high stability in dry air.
Several studies report using CH3NH3PbI3 perovskite nanocrystals as sensitizers in photoelectron-chemical cells with liquid electrolyte [4-6]. However, the performance of these systems rapidly declines due to dissolution of the perovskite.
Snaith et al. [7] and Grätzel et al. [8] reported on efficient hybrid organic-inorganic solar cells, based on a meso-superstructured organo halide perovskite, yielding power conversion efficiency of exceeding 10%.
In addition, Etgar et al.[9] reported on the use of hole-conductor free perovskite heterojunction solar cells. The authors found that the lead halide perovskite could transport holes, in addition to its functionality as an absorber, achieving impressive photovoltaic performance with power conversion efficiency of more than 7% under low light intensity. Etgar et al also discloses mesoscopic CH3NH3PbI3/TiO2 heterojunction solar cells, comprising mesoscopic methylammonium lead iodide (CH3NH3PbI3) perovskite/TiO2, produced by deposition of perovskite nanoparticles from a solution of CH3NH3I and PbI2 in γ-butyrolactone on a 400 nm thick film of TiO2 (anatase) nanosheets. The presence of TiO2 was found critical as the authors held that TiO2 was needed as a scaffold mainly in order to increase the surface area.